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    Optimal detailed design and performance assessment of natural gas pressure reduction stations system equipped with variable inlet guide vane radial turbo-expander for energy recovery

    , Article Journal of Natural Gas Science and Engineering ; Volume 96 , 2021 ; 18755100 (ISSN) Ebrahimi Saryazdi, S. M ; Rezaei, F ; Saboohi, Y ; Sharif University of Technology
    Elsevier B.V  2021
    The turbo-expander system is utilized instead of the pressure regulator to avoid exergy destruction occurring in gas pressure reduction systems. However, due to the variation of natural gas input conditions such as mass flow rate, the sustainable performance of this technology is challenging. In this study, at first, the optimal system design of gas pressure reducing station equipped with radial expansion turbine is performed. It is based on economic and exergy analyses as well as considering geometric, fluid, thermodynamic constraints of components and the systematic constraints. To do so, detailed design models of main components including mean-line design model of radial turbine,... 

    Turboexpander Technology Development Model and Display Roadmap for Pressure Reducing System based Energy Recovery by Turboexpander

    , M.Sc. Thesis Sharif University of Technology Ramezani, Roohollah (Author) ; Saboohi, Yadollah (Supervisor)
    High pressure natural gas is transported from processing plants to end users via a network of natural gas system. Pressure reduction along the transport system is compensated in compressor stations. High pressure natural gas flows in to distribution network in demand center which operates at medium pressure. Medium pressure gas is transferred to end users who can use natural gas with low pressure. Therefore, pressure of natural gas is reduced consequently when gas flows from transport systems to distribution network and end users. Work is dissipated during pressure reduction which otherwise could be converted in to power.A technology that could be utilized for conversion of pressure work in... 

    Development of Dynamic Model for Turbo Expander Performance Assessment in Unstable State of Natural Gas Distribution Network

    , M.Sc. Thesis Sharif University of Technology Rezaiee, Farzaneh (Author) ; Saboohi, Yadollah (Supervisor)
    In line with the energy policies of the country, which is based on the development of the natural gas system, the natural gas transmission sector has also had a significant expansion during this period, especially in recent years. On the other hand, the promotion of energy efficiency has been a major issue in energy policies and programs. Therefore, the necessity of expanding and developing the rational use of energy has been considered more than ever. The use of energy recovery technologies will be an effective step in this regard. Owing to the wide expansion of gas pressure regulating stations in Iran and the high potential losses in pressure relief valves, substituting an expansion... 

    Hydrodynamic Performance of Squat Submarine Equipped with Passive Pressure Drag Reductions

    , Ph.D. Dissertation Sharif University of Technology Sarraf, Sadyar (Author) ; Abbaspour, Madjid (Supervisor) ; Mohtasham Dolatshahi, Kiarash (Supervisor) ; Sani, Mahdi (Co-Supervisor)
    This research empirically examines the hydrodynamic performances of squat submarines under the resistance and wave tests, besides the numerical investigation of pressure drag reduction techniques. Submarines are limited for public use due to military classification issues and being expensive. This research introduces a new squat submarine in order to enable underwater exploration. This squat submarine has a 9- person capacity as a manned midget submersible using specific geometries of length-over-depth ratios (L/D) below four. The cause of such selection is to provide better visibility for the passengers to research and explore the sea. However, the geometrical features considerably change... 

    Distilled water production with combination of solar still and thermosyphon heat pipe heat exchanger coupled with indirect water bath heater – Experimental study and thermoeconomic analysis

    , Article Applied Thermal Engineering ; Volume 176 , 2020 Rastegar, S ; Kargarsharifabad, H ; Rahbar, N ; Shafii, M. B ; Sharif University of Technology
    Elsevier Ltd  2020
    The aim of this study is to provide a solution for supplying distilled water used in indirect water bath heaters in the pressure reduction stations. A particular type of distilled water production system consists of a typical solar still and a heat pipe heat exchanger was constructed for recovering heat from the exhaust of an indirect gas heater. The system was tested under the climatic conditions of Semnan-Iran. Experimental results showed that in active type, the average daily production rate of distilled water would be 2.06 times higher than passive type. Also, in the proposed system, the average daily energy efficiency and the exergy efficiency would be 65.5% and 41% higher than the... 

    Simulation and Estimation of Power Generation in Natural Gas Network by Micro Turboexpanders

    , M.Sc. Thesis Sharif University of Technology Hejazi, Bijan (Author) ; Farhadi, Fatolah (Supervisor)
    This thesis studies the economic feasibility of replacing a throttling valve with an expansion turbine in a city gate station for the purpose of distributed electricity generation through exergy recovery from pressurized natural gas. Conventionally, high pressure natural gas stream enters a pressure reduction station with its physical exergy completely destroyed in an irreversible Joule-Thompson effect of a throttling valve. To avoid hydrate formation at the outlet of the turboexpander, the inlet stream should be preheated. Although pressure reduction stations are inherently subject to seasonal fluctuations of inlet natural gas pressure and flow rate, the preheating temperature should be... 

    Baseline Design of the Exergy Recovery and Solar Heating System at the Gas Pressure Reduction Station and its Technical, Economical, and Environmental Assessments

    , M.Sc. Thesis Sharif University of Technology Talaei, Mohammad (Author) ; Saboohi, Yadollah (Supervisor)
    As producing and consuming of natural gas has increased in recent years, improving natural gas distribution and transfer network systems has become vital. Pressure reduction station (PRS) is an important part of the natural gas network. Common PRSs are facing two issues: first is the pressure reduction technology, which is throttling valve that destroys the exergy of the high pressure flow. The solution is to utilize turbo-expander instead which can recover the energy. Second is the preheating technology which is boiler and water bath heater in the common systems that cause environmental problems. Using solar collectors is one of the best solution based on the literature. Since the solar... 

    Dynamic System Optimal Design Model: Designing and Evaluation of Turboexpander System Operation

    , Ph.D. Dissertation Sharif University of Technology Ebrahimi Saryazdi, Mohammad (Author) ; Saboohi, Yadoolah (Supervisor)
    According to Iran’s energy policies, the natural gas transmission pipeline has expanded significantly over the last decade. Moreover, improving energy efficiency is known as a key strategy in energy policies and programs. Therefore, the need for expansion and development of the rational use of energy has received more and more attention. The use of technologies aimed at energy recovery will be an effective step in this regard. Pressure regulators are most commonly used to reduce this pressure in Iran as one of the significant sources of exergy destruction in Iranian gas transmission system. The turbo-expander system is a kind of technology applied in gas pressure reduction stations to... 

    Experimental determination of hydrate phase equilibrium curve for an Iranian sour gas condensate sample

    , Article Journal of Natural Gas Science and Engineering ; Volume 9 , November , 2012 , Pages 11-15 ; 18755100 (ISSN) Kamari, E ; Oyarhossein, M ; Sharif University of Technology
    Iran's proved natural gas reserves are the world's second largest. Mainly, because of climate changes and different reservoirs' characterizations, studying the behavior of production fluids and their transportation is essential. One of the main problems which occurs in the gas reservoirs is related to the hydrate formation while producing from a well, either in production strings or production lines (before and after choke). Effective parameters which influence the formation of hydrates are: high pressure, low temperature and water presence; and therefore, the high possibility of having this phenomenon in Iranian reservoirs is quite obvious especially in cold climates and for gas wells.... 

    The impact of CO2 injection and pressure changes on asphaltene molecular weight distribution in a heavy crude oil: An experimental study

    , Article Petroleum Science and Technology ; Volume 28, Issue 17 , 2010 , Pages 1728-1739 ; 10916466 (ISSN) Sadeqimoqadam, M ; Firoozinia, H ; Kharrat, R ; Ghazanfari, M. H ; Sharif University of Technology
    This work concerns observing the pressure as well as CO2 mole percentage effects on asphaltene molecular weight distributions at reservoir conditions. A high-pressure, high-temperature asphaltene measurement setup was applied, and the amount of precipitated asphaltene at different pressures as well as CO2 mole percentage in an Iranian heavy crude oil was measured. Moreover, the asphaltene molecular weight distributions during titration of crude oil with different n-alkanes were investigated. The gel permeation chromatography (GPC) apparatus was used for characterization of asphaltene molecular weight under different conditions. It has been observed that some thermodynamic changes such as...